Antenna and oscillator coil unit



y 0, 1950 R. B. BRODE ETAL 2,509,903

ANTENNA AND OSCILLATOR COIL UNIT Filed March 20, 1943 3 Sheets- Sheet l I I /'l6' l l /8 Fl a1.

.L '7 INVENTORS ROBERT B. 50 5.

RRF.

BY R G May 30, 1950 R. a. BRODE. ETAL,

ANTENNA AND OSCILLATOR COIL UNIT 3 Sheets-Sheet 2 Filed March 20, 1943 ay 30, 1950 R. B. BRODE EI'AL 2,509,903

ANTENNA AND OSCILLATOR con UNIT Filed March 20, 1943 3 Sheets-Sheet 3 mVENTORS BY I no NEv I Patented May 30, 1950 ras ANTENNA AND OSCILLATOR COIL UNIT tary of the Navy Application March 20, 1943, Serial No. 479,948

9 Claims. 1

This invention relates to radio apparatus and more particularly to a novel unit for use in connection with an oscillating circuit to receive radio frequency oscillations therefrom for transmission or to receive transmitted radio waves for conduction to the circuit. The new unit is simple and rugged in construction and is adapted for manufacture at low cost by the practice of a novel method which forms part of the invention.

While the invention is adapted for general use in radio apparatus, it may be used to particular advantage in radios where unusual ruggedness and strength are desired. Accordingly, for illustrative purposes, the invention will be described in connection with a radio-controlled proximity fuze for projectiles, of the type disclosed in a copending application of Merle A. Tuve and Richard 13. Roberts, Serial No. 471,388, filed January 6, 1943. Also, while the radio unit of our invention may take the form of either an oscillator coil or an antenna, it will be described and illustrated as a combination antenna and oscillator coil unit, because in that form it is admirably suited for use in the proximity fuze of the aboveidentifled application.

It has been proposed heretofore to provide a radio-controlled proximity fuze having an antenna made of aluminum or other light weight metal coupled to the oscillator coil and formed in a generally conical shape so that it may be located at the nose of the projectile. Although fairly satisfactory results have been obtained with the prior antennae, some dificulty has been experienced in that they are often displaced by rough handling or other causes, due to their exposed position at the nose of the projectile, or by the force of set-back incident to firing the projectile, with the result that the fuses are rendered inoperative or are detonated prematurely. Also, the oscillator coil is subject to displacement by the force of set-back, with the same result.

One object of the present invention, therefore,

- resides in the provision of a novel antenna unit which overcomes this objection to the prior antenna, by reason of its being made of a coating of metal sprayed or otherwise applied to an insulating body.

Another object of the invention is to provide a novel oscillator coil unit comprising a spiral coating of metal on an insulating body, whereby the coil efiectively resists displacement due to a force of set-back or other cause. Preferably, the spiral coating is sprayed or otherwise applied on an insulating body in the form of an oscillator block, and the antenna is coated on the same block adjacent the spiral coating, so

that the coil and antenna are electrically connected. With this construction, the coil, because of the manner in which it is mounted, serves not only as an inductance in the oscillator but also as a screen for preventing premature functioning of the oscillator due to electro-static charges.

A further object of the invention resides in the provision of a novel method of making a radio unit of the character described. According to the invention, a coating of metal is applied to an insulating body, as by spraying the metal while it is molten, and part of the coating is then removed to define the antenna or the oscillator coil, or both. The excess coating may be removed by masking the insulating body before the coating is applied, to cover the area from which the coating is to be removed, and then removing the mask after the coating is applied. Alternatively, the insulating body may be recessed to define the antenna or the coil, or both, and after the coating is applied the metal outside the recess may be removed.

These and other objects of the invention may be better understood by reference to the accompanying drawings, in which:

Fig. 1 is a side view of a combination antenna and oscillator coil unit made in accordance with the invention;

Fig. 2 is a view similar to Fig. 1, with parts broken away;

Fig. 3 is a perspective view of a modified form of the new unit, showing the insulating body before the metal coating is applied;

Fig. 4 is a longitudinal sectional view of part of the insulating body shown in Fig. 3, with the metal coating applied thereto;

Fig. 5 is a view similar to Fig. 4, showing the unit after the excess coating is removed;

Fig. 6 is a, perspective view of another form oi the unit, and

Fig. 7 is a schematic view of a projectile embodying the invention.

Referring to the drawings, the invention as there shown is adapted for use in a projectile comprising a metal casing I and a hollow metal nose portion ll threaded or otherwise secured in the forward end of the casing. The nose portion and the casing contain a radio-controlled proximity fuze I 2 which preferably includes oscillator, amplifier, battery and thyratron units (not shown), the parts being arranged to trigger the thyratron due to reflection of radio waves from the oscillator by a target, such as airplane, in proximity to the projectile, as described in said copending application, Serial No. 471,388. The thyratron, when triggered, causes detonation oi. the usual booster It so as to explode the main charge in the projectile.

The oscillator unit of the proximity fuze includes an oscillator coil [5, which corresponds to the coil 4| in the fuze oi the above identified application, the coil l5 being mounted on an oscillator block l8 of insulating material secured in any suitable manner in the forward end of the nose portion II. The block I6 projects from the nose portion II and has a generally conical part constituting the nose of the projectile and forming a' continuation of the tapered contour of the nose portion. The coil I 5 comprises a spiral coating of metal on the conical surface 01' the block l6 intermediate its ends, one end of the coil being grounded to the projectile casing by contact with the forward end of the nose portion II, as shown at IT. At its opposite end, the coil l5 terminates in an antenna l8 formed by a solid coating of metal on the reduced end portion of the block l6. As described in the above identified application, by grounding the oscillator coil l5 to the projectile casing through the contact H, a relatively high radio frequency voltage may be applied to the antenna l8 from the oscillator coil.

The metal coating l5, l8 may be applied in any desired manner, as by covering the surface to the rear of the coil l5 and the spaces l9 between the turns of the coil with a mask (not shown) before the coating is applied, spraying the metal while molten on the block I6, and then removing the mask. The block may be made of any suitable insulatin material, such as Lucite, and when the metal coating has hardened, its adhesion to the block makes it extremely resistant to displacement.

The unit shown in Figs. 3 to 5, inclusive, comprises a generally conical oscillator block 2|, the tapered end portion of which is reduced, as shown at 22, to form a shoulder 23. A helical groove 24 is formed in the conical surface of the block and communicates at one end with the reduced portion 22. In the practice of our new method, a coating of metal 25 is applied to the surface of the block 2|, as by spraying molten metal on the surface, so as to cover the recess 22 and the helical groove 24. When the coating has hardened, the metal outside the groove and the recess is removed, as by a milling operation, with the result that the remaining metal in the groove forms a helical coil 250. connected at one end to an antenna in the recess 22.

The unit shown in Fig. 6 comprises a generally conical oscillator block 21 having a spiral coating of metal 28 extending from the tapered end of the block toward the base so as to form a coil. The coating may be conveniently applied by masking the spaces between the turns of the coil before spraying the metal, and then removing the mask after the metal is sprayed, or by forming a helical groove in the block and removing the excess metal outside the groove after the metal is applied. The coil 28 is connected intermediate its ends to a conductor 29, as by means of a tap III, the conductor extending through a passage in the block 21 to the base of the block where it is connected in the oscillator circuit. with this construction, the part of the coil 28 above the tap 30 constitutes an antenna, while the part below the tap serves as an oscillator coil.

It will be apparent that the new unit may be manufactured at low cost in accordance with the method of our invention, since only a few simple operations are required and the operations can be performed readily by unskilled labor. When the antenna and coil have hardened on the block, they form an integral part thereof and may be subjected to mechanical shock and rough handling without displacement. The unit may be made in a compact form, and by mounting the coil on the exterior of the oscillator block, the coil serves as an electro-static screen for the oscillator.

We claim 1. In a radio-controlled projectile, an insulating body forming part of the projectile, a spiral coating of metal on the body forming an oscillator coil, and a coating of metal on the body and defining an antenna.

2. In a radio-controlled projectile having a metal casing, an insulating body on the projectile, a spiral coating of metal on the body forming an oscillator coil, means for grounding the coil on the casing, and a coating of metal on the body and defining an antenna.

3. An antenna and oscillator coil unit comprisin an insulating body, a spiral coating of metal on the body forming an oscillator coil, and a metal antenna coated on the body for receiving oscillations from the coil.

4. In a radio-controlled projectile, a nose comprising a generally conical insulating body, a metal antenna coated on the reduced end portion of the body, and a spiral coating of metal on the body to the rear of the antenna and formin an oscillator coil connected to the antenna.

5. In a radio-controlled projectile, a nose comprising a generally conical insulating body having a spiral groove in the intermediate portion 01' its conical surface, the groove terminating in a reduced portion of the body, a metal coating in the groove forming an oscillator coil, and a metal antenna coated on said reduced portion and connected to the coil to receive oscillations therefrom.

6. The method of forming an antenna and oscillator coil unit having an insulating body, which comprises forming a reduced portion on the body and a spiral groove communicating with the reduced portion. applying a coating of metal on the body, and removing the metal from th body outside the groove and the reduced portion.

'7. In a rad o controlled projectile. the combination of a tapered body of insulating material forming the nose of the projectile, and a spiral coatin of metal on the body forming an oscillator coil.

8. In a radio controlled projectile having a asoaaos tapered insulating body forming the nose of the I projectile, the combination with an exterior metal coating forming a helical coil, of a metallic coating on an adjacent portion of the body'forming an antenna electrically connected with the coil.

9. For use on a radio controlled projectile having an insulating body, the combination of a spiral coating of metal forming a coil, and a metal coated antenna on the body and electrically'coupled to the coil. 7

ROBERT B. BRODE.

ROBERT G. FERRIS.

6 REFERENCES CITED The following references are of record in the file of this patent:

5 UNITED STATES PATENTS Number Name Date 1,256,599 Schoop Feb. 19, 1918 2,193,555 Deren Mar. 12, 1940 2,281,284 Hammond Apr. 28, 1942 in 2,297,488 Luderitz Sept. 29, 1942 FOREIGN PATENTS Number Country Date 19,318 Great Britain 1914 91,592 Sweden Dec. 22, 1937 502,460 Great Britain Mar. 17, 1989 546,488 Great Britain 1942 

